Nanomaterials have attracted considerable interest owing to their unique physicochemical properties.The wide application of nanomaterials has raised many concerns about their potential risks to human health and the environment.Metal oxide nanopartides（MONPs）,one of the main members of nanomaterials,have been applied in various fields,such as food,medicine,cosmetics,and sensors.This review highlights the bio-toxic effects of widely applied MONPs and their underlying mechanisms.Two main underlying toxicity mechanisms,reactive oxygen species（ROS）-and non-ROS-mediated toxidties,of MONPs have been widely accepted.ROS activates oxidative stress,which leads to lipid peroxidation and cell membrane damage.In addition,ROS can trigger the apoptotic pathway by activating caspase-9 and-3.Non-ROS-mediated toxicity mechanism includes the effect of released ions,excessive accumulation of NPs on the cell surface,and combination of NPs with specific death receptors.Furthermore,the combined toxicity evaluation of some MONPs is also discussed.Toxicity may dramatically change when nanomaterials are used in a combined system because the characteristics of NPs that play a key role in their toxicity such as size,surface properties,and chemical nature in the complex system are different from the pristine NPs.
More and more nanomaterials enter the environment along with their production, application and deposal. They may alter the biological effect of pollutants already existing in the real environment by different interactions. Therefore efforts should also be paid to investigate the combined toxicity of nanomaterials and pollutants. Herein, we studied the combined toxicity of oxi- dized multi-walled carbon nanotubes （O-MWCNTs） and zinc ions on ceils. It is found that cytotoxicity of the combined O-MWCNTs and zinc ions elevates significantly, compared with O-MWCNTs or zinc ions alone. This result comes from the assays of cell morphology, cell viability and proliferation, cell membrane integrity, mitochondrial membrane potential and cell apoptosis. Mechanism studies indicate that O-MWCNTs absorb zinc ions and form slight aggregation. These enhance remark- ably the cellular uptake of O-MWCNTs, and thus induce the death of cells by bringing in more zinc ions into cells. Our study indicates that the existence of nanomaterials could change the bioconsequence of other pollutants and emphasizes the im- portance of the combined toxicity research in the presence of nanomaterials.
Lin WangJia-Hui LiuZheng-Mei SongYi-Xin YangAoneng CaoYuanfang LiuHaifang Wang
Water pollution has become serious environmental problem nowadays. Advanced oxidation processes(AOP) have been widely applied in water treatment.However, traditional Fenton reaction based on Fe2﹢-H2O2 system has obvious drawbacks, which limit its applications In this study, magnetic Fe3O4core-C shell nanoparticles(Fe3O4@C NPs) were prepared for the decoloration of methylene blue(MB) via the co-precipitation followed by the hydrothermal dehydrogenation of glucose. Fe3O4@C NPs showed high catalytic activity of the decoloration of MB through the decomposition of H2O2 in Fenton-like reactions. Fe3O4@C NPs had much higher activity than bare Fe3O4 cores, suggesting the coating of carbon enhanced the catalytic activity. The performance of Fe3O4@C NPs was better at lower pH and higher temperature, but was significantly inhibited in the presence of radical scavenger tertiary butanol. Fe3O4@C NPs could be magnetic separated and regenerated, and maintained with very good catalytic activity. The implication for the applications of Fe3O4@C NP-catalyzed Fenton-like reactions in water treatment was discussed.
